“Water, water, everywhere ...” – Table Mountain and the water crisis

“Nor any drop to drink,” continued Samual Taylor Coleridge’s Rime of the Ancient Mariner, and with only three months of water left in Cape Town at the time of writing, it seems we face the same dilemma as the famous poem’s hapless sailor. Surrounded by blue oceans, we can only watch as our drinking water diminishes every day under a cloudless sky.

Waterfalls run all over Table Mountain after rain, filling rivers and reservoirs.

(Images: Dominic Chadbon)

Fingers are pointing in different directions, but the root cause of the water crisis lies in diminishing rainfall coupled with rapid urbanisation and increased demand for potable water. When you live in an environment that receives 70% of its annual rain in three or four short winter months, then just one poor rainy season is enough to knock Cape Town to its knees.

And there’s not much to look forward too: in a world of rising temperatures, it is predicted that Cape Town will receive between 10 and 25% less rain in future. Desalination plants seem to be the answer, but they are expensive and will take years to build; we’re running out of water NOW.

Water and fynbos

Does Table Mountain hold the key – at least in the short term? As described in an earlier blog, the fynbos vegetation plays a huge role in water retention. Unlike alien pines and blue gums that soak up water like blotting paper, fynbos not only allows most of the rainwater to run off into our rivers and reservoirs, but holds water in the high wetlands too, slowly releasing it throughout the year. After all, it is the permanent stream coming down Platteklip Gorge near the Cableway that is the reason for Cape Town’s establishment in the 17th century.

Looking underground

The mountain ranges that surround Cape Town are home to some of the wettest places in the Western Cape.

So perhaps the answer is to rely not on water from the surface as we do now (98.5% of our drinking water comes from reservoirs), but from underground. There are large manmade reservoirs on Table Mountain itself, but they have been unable to supply Cape Town with enough water for a hundred years, and the big reservoirs out of town are running dry. However, sitting below the grey sandstone rocks of the Table Mountain group (the craggy mountains of the Western Cape) are billions of cubic metres of water – fresh, drinkable and crystal clear – in natural aquifers.

The challenge, of course, lies in its extraction: it would need to be both economically and environmentally viable. And while tapping into an existing water source is far cheaper that building more dams or desalination plants, what would the cost be to the natural ecology? Would the stream down Platteklip Gorge still run? Would we care if it did or not when faced with empty taps in the kitchen?

It is no exaggeration to say that Cape Town is facing a water crisis. And even if we get good rains this winter, it will take up to three years to replenish our reservoirs; next summer may be even more testing than this one. Time to tap the aquifer? There was exploratory drilling into the Table Mountain aquifer a decade or so ago; we might see rather more urgent progress in the coming months and years – let’s just hope we are accessing a sustainable resource rather than draining our last water supply.